Plating device

ABSTRACT

A plating device for plating a substrate includes a plating solution container for retaining a plating solution. The plating solution container has a sidewall and an opening portion surrounded with the sidewall. Further, the plating device includes a holding member for holding the substrate so that the substrate faces the opening portion of the solution container and is situated away from the plating solution container; a cathode electrode for contacting with an outer circumferential portion of the substrate; an anode electrode for contacting the plating solution in the plating solution container; a plating solution supply device for supplying the plating solution into the plating solution container so that the plating solution overflows through a space between the plating solution container and the substrate after the plating solution contacts with the substrate; and a through hole formed in the sidewall of the plating solution container.

BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT

The present invention relates to a plating device. In particular, thepresent invention relates to a plating device for plating asemiconductor wafer or a semiconductor substrate.

A conventional plating device is provided for uniformly plating asemiconductor wafer. Various types of conventional plating devices havebeen proposed (refer to Patent References 1 to 4).

-   Patent Reference 1: Japanese Patent Publication No. 2003-306793-   Patent Reference 2: Japanese Patent Publication No. 08-74088-   Patent Reference 3: Japanese Patent Publication No. 2000-195823-   Patent Reference 4: Japanese Patent Publication No. 2000-328291

FIG. 7 is a schematic sectional view showing a conventional platingdevice 2′. FIG. 8 is a schematic plan view showing the conventionalplating device 2′. It is noted that a wafer pressing member 88′ isomitted in FIG. 8.

As shown in FIG. 7, in the conventional plating device 2′, a ring member80′ is disposed on a circumferential portion outside an upper portion ofa cup portion 20′. Electrode pins 70′ are disposed on the ring member80′ with an interval of 120 degrees. A wafer placing portion 72′ isdisposed at a distal end portion of each of the electrode pins 70′.Accordingly, a wafer 90′ is placed on the wafer placing portions 72′ atan outer circumferential portion thereof. More specifically, the wafer90′ is placed on the wafer placing portions 72′ such that a surface 90′(a plating surface) of the wafer 90′ faces toward the cup portion 20′ (alower side in FIG. 7).

Further, in the conventional plating device 2′, the wafer pressingmember 88′ is placed on a backside surface 94′ of the wafer 90′, so thatthe wafer pressing member 88′ presses the wafer 90′ toward the lowerside in FIG. 7. Accordingly, the wafer 90′ is fixed with the waferpressing member 88′ and the wafer placing portions 72′ of the electrodepins 70′. A space 82 is created between the surface 92′ of the wafer 90′and an upper end portion 24′ of the cup portion 20′.

Further, in the conventional plating device 2′, an anode plate 50′ isdisposed on a bottom circumferential portion 26′ of the cup portion 20′.An anode electrode 52′ is provided for fixing the anode plate 50′.

In the conventional plating device 2′, a plating solution 60′ containingcopper ions (Cu²⁺) is supplied into the cup portion 20′ through a supplyinlet 22′ formed in a bottom portion 28′ of the cup portion 20′ at acenter thereof. Then, the plating solution 60′ flows toward a centerportion of the wafer 90′ placed at the upper portion of the cup portion20′. Afterward, the plating solution 60′ flows toward an outercircumferential portion of the wafer 90′, and then is overflowed throughthe space between the wafer 90′ and the upper end portion 24′ of the cupportion 20′.

In the conventional plating device 2′, a voltage applied between theanode plate 50′ and the electrode pins 70′, so that an electricalcurrent flows between the anode plate 50′ and the electrode pins 70′.Accordingly, an electrical current flows through the wafer 90′, so thatthe surface 92′ of the wafer 90′ is plated.

In the conventional plating device 2′ shown in FIG. 7, the electricalcurrent flows to the outer circumferential portion of the wafer 90′through the electrode pins 70′. Accordingly, as opposed to the centerportion of the wafer 90′, an electrical current density tends toincrease at the outer circumferential portion of the wafer 90′. As aresult, the surface 92′ of the wafer 90′ tends to be plated at a greaterrate at the outer circumferential portion of the wafer 90′.

FIG. 9 is a schematic plan view of the wafer 90′ after the wafer 90′ isplated with the conventional plating device 2′. As shown in FIG. 9, whenthe wafer 90′ is plated with the conventional plating device 2′, anouter circumferential portion 96′ of the wafer 90′ tends to have alarger plating thickness as opposed to that at a center portion 95′ ofthe wafer 90′. Further, a peripheral region 97′ near the electrode pin70′ tends to have a still larger plating thickness, thereby making itdifficult to obtain a uniform plating thickness.

In view of the problems described above, an object of the presentinvention is to provide a plating device capable of solving the problemsof the conventional plating device. In the present invention, it ispossible to obtain a plating film with a uniform thickness.

Further objects and advantages of the invention will be apparent fromthe following description of the invention.

SUMMARY OF THE INVENTION

In order to attain the objects described above, according to a firstaspect of the present invention, a plating device for plating asubstrate includes a plating solution container for retaining a platingsolution. The plating solution container has a sidewall and an openingportion surrounded with the sidewall.

Further, the plating device includes a holding member for holding thesubstrate so that the substrate faces the opening portion of thesolution container and is situated away from the plating solutioncontainer; a cathode electrode for contacting with an outercircumferential portion of the substrate; an anode electrode forcontacting the plating solution in the plating solution container; aplating solution supply device for supplying the plating solution intothe plating solution container so that the plating solution overflowsthrough a space between the plating solution container and the substrateafter the plating solution contacts with the substrate; and a throughhole formed in the sidewall of the plating solution container.

According to a second aspect of the present invention, the through holemay be arranged to face the cathode electrode.

According to a third aspect of the present invention, the through holemay be arranged at a position to face the cathode electrode and anotherposition to not face the cathode electrode.

According to a fourth aspect of the present invention, the platingdevice may further include an opening size adjusting member foradjusting an opening size of the through hole.

In the present invention, the plating device is capable of forming aplating film with a uniform thickness.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view showing a plating device accordingto a first embodiment of the present invention;

FIG. 2 is a schematic plan view showing the plating device in a statethat a wafer pressing member is omitted according to the firstembodiment of the present invention;

FIGS. 3(A) and 3(B) are schematic sectional views showing a wafer to beplated with the plating device according to the first embodiment of thepresent invention, wherein FIG. 3(A) is a schematic sectional viewshowing the wafer before the plating device plates the wafer and FIG.3(B) is a schematic sectional view showing the wafer after the platingdevice plates the wafer;

FIG. 4 is a schematic sectional view showing a plating device takenalong a line 4-4 in FIG. 2 according to a second embodiment of thepresent invention;

FIG. 5 is a schematic sectional view showing a plating device takenalong the line 4-4 in FIG. 2 according to a third embodiment of thepresent invention;

FIG. 6 is a schematic plan view showing a plating device in a state thata wafer pressing member is omitted according to a fourth embodiment ofthe present invention;

FIG. 7 is a schematic sectional view showing a conventional platingdevice;

FIG. 8 is a schematic plan view showing the conventional plating devicein a state that a wafer pressing member is omitted; and

FIG. 9 is a schematic plan view showing a wafer plated with theconventional plating device.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Hereunder, preferred embodiments of the present invention will beexplained with reference to the accompanying drawings.

First Embodiment

A first embodiment of the present invention will be explained. FIG. 1 isa schematic sectional view showing a plating device 1 according to thefirst embodiment of the present invention. FIG. 2 is a schematic planview showing the plating device 1 in a state that a wafer pressingmember 88 is omitted according to the first embodiment of the presentinvention.

As shown in FIGS. 1 and 2, the plating device 1 includes a base portion10, a cup portion 20 disposed on the base portion 10, a ring portion 80disposed above an upper portion of the cup portion 20 at an outercircumferential portion thereof; electrode pins 70 disposed on the ringportion 80; and the wafer pressing member 88.

In the embodiment, the base portion 10 has a supply opening portion 12at a center portion thereof for supplying a plating solution 60. The cupportion 20 is disposed on the base portion 10. The cup portion 20includes a sidewall portion 30 and a bottom portion 28.

In the embodiment, the plating device 1 has an opening portion 31surrounded with the sidewall portion 30 at the upper portion of the cupportion 20, so that the sidewall portion 30 and the bottom portion 28form a plating solution bath 21. A supplying opening portion 22 isformed in the bottom portion 28 at a center portion thereof forsupplying the plating solution 60 into the plating solution bath 21. Thesupply opening portion 12 formed in the base portion 10 communicateswith the supplying opening portion 22 formed in the cup portion 20.

In the embodiment, the ring portion 80 is disposed above the upperportion of the cup portion 20 at the outer circumferential portionthereof, and the electrode pins 70 are disposed on the ring portion 80with an equal interval for functioning as a cathode electrode. Theelectrode pins 70 are disposed, for example, at three locations forplating a six-inch wafer or six locations for plating an eight-inchwafer. Accordingly, the electrode pins 70 are disposed with the 120degree interval or the 60 degree interval, respectively. The followingdescription, the electrode pins 70 are disposed at three locations as anexample.

In the embodiment, a wafer placing portion 72 is formed at a distal endportion of each of the electrode pins 70, so that an outercircumferential portion of a wafer 90 is placed on the wafer placingportions 72. Further, the outer circumferential portion of the wafer 90contacts with the wafer placing portions 72. The wafer 90 is placed suchthat a front surface 92 thereof (a plating surface) faces an openingportion 31 of the cup portion 20 downwardly in FIG. 1 (toward the cupportion 20). The wafer pressing member 88 presses the wafer 90 from abackside surface 94 thereof downwardly in FIG. 1, so that the waferpressing member 88 and the wafer placing portions 72 of the electrodepins 70 fix the wafer 90. A space 82 is formed between the front surface92 of the wafer 90 and an upper edge portion 24 of the cup portion 20.

In the embodiment, slits 32 are formed in the sidewall portion 30 of thecup portion 20 near the upper edge portion 24 thereof to penetrate thesidewall portion 30. More specifically, the slits 32 are formed at sixlocations with an equal interval of 60 degrees. Three of the slits 32are disposed just below the electrode pins 70 to face the electrode pins70.

In the embodiment, an anode plate 50 is disposed on a bottomcircumferential portion 26 of the cup portion 20, and an anode electrode52 fixes the anode plate 50. The anode plate 50 and the node electrode52 are arranged to contact with the plating solution 60. Further, theanode electrode 52 and the electrode pins 70 are connected to a platingpower source (not shown).

In the embodiment, a plating solution container 40 is arranged outsidethe cup portion 20. A pump 42 is connected to the supply opening portion12 of the base portion 10 for supplying the plating solution 60 from theplating solution bath to the plating solution bath 21.

In the embodiment, the plating solution 60 contains, for example, copperions (Cu²⁺). When the pump 42 supplies the plating solution 60 from theplating solution bath to the plating solution bath 21 in the cup portion20 through the supply opening portion 12 of the base portion 10 and thesupplying opening portion 22 of the cup portion 20, the plating solution60 flows toward a center portion of the wafer 90 placed at the upperportion of the cup portion 20, so that the plating solution 60 contactswith the front surface 92 (the plating surface) of the wafer 90.

Afterward, the plating solution 60 flows toward the outercircumferential portion of the wafer 90, and overflows through the space82 between the upper edge portion 24 of the cup portion 20 and the wafer90. Accordingly, the plating solution 60 flows through a space 83between the upper edge portion 24 of the cup portion 20 and the ringportion 80, so that the plating solution 60 returns from the platingsolution bath 21 to the plating solution container 40 arranged outsidethe cup portion 20. Further, the plating solution 60 flows through theslits 32 formed in the sidewall portion 30 of the cup portion 20, sothat the plating solution 60 returns from the plating solution bath 21to the plating solution container 40 arranged outside the cup portion20.

In the embodiment, when the wafer 90 is plated, a voltage is appliedbetween the anode plate 50 and the electrode pins 70 to flow anelectrical current there between. Accordingly, the electrical currentflows through the wafer 90, so that the front surface 92 of the wafer 90is plated.

A method of plating the front surface 92 of the wafer 90 will beexplained in more detail next with reference to FIGS. 3(A) and 3(B).FIGS. 3(A) and 3(B) are schematic sectional views showing the wafer 90to be plated with the plating device 1 according to the first embodimentof the present invention. More specifically, FIG. 3(A) is a schematicsectional view showing the wafer 90 before the plating device 1 platesthe wafer 90, and FIG. 3(B) is a schematic sectional view showing thewafer 90 after the plating device 1 plates the wafer 90.

When the plating device 1 plates the wafer 90, first, a sheet payer 110is disposed on the entire surface of the front surface 92 (the platingsurface) of the wafer 90. Then, a resist layer 112 is selectively formedon the sheet layer 110, so that an opening portion 114 is formed.Instead of the resist layer 112, a resist film may be disposed on thesheet layer 110.

In the next step, while the sheet layer 110 is connected to theelectrode pins 70, a voltage is applied between the anode plate 50 andthe electrode pins 70 to flow an electrical current there between. As aresult, an electrical current flows through the sheet layer 110 formedon the front surface 92 of the wafer 90. Accordingly, the following ionreaction occurs on the front surface 92 of the wafer 90, so that acopper plating layer 120 is formed in the opening portion 114 of theresist layer 112 as shown in FIG. 3(B).

Cu²⁺+2e⁻→Cu

In general, the electrical current flows from the outer circumferentialportion of the wafer 90 through the electrode pins 70. Accordingly, acurrent density tends to be higher at the outer circumferential portionof the wafer 90 as compared with the center portion of the wafer 90.

In the plating device 1 according to the embodiment, the slits 32 areformed in the sidewall portion 30 of the cup portion 20. Accordingly,the plating solution 60 flows out from the plating solution bath 21through the slits 32 formed in the sidewall portion 30 of the cupportion 20 as well. As a result, a reduced amount of the platingsolution 60 overflows through the space 82 between the upper edgeportion 24 of the cup portion 20 and the wafer 90, so that a reducedamount of the plating solution 60 contacts with the outercircumferential portion of the wafer 90.

Accordingly, an amount of copper ions Cu²⁺ supplied to the outercircumferential portion of the wafer 90 for forming the plating layer120 decreases. As a result, growth of the plating layer 120 at the outercircumferential portion of the wafer 90 is restricted. Accordingly, itis possible to prevent the plating layer 120 from excessively increasingat the outer circumferential portion of the wafer 90, thereby making itpossible to obtain the plating layer 120 with a uniform thickness overthe entire surface of the wafer 90.

As described above, in the embodiment, the slits 32 are formed in thesidewall portion 30 of the cup portion 20 near the upper edge portion 24thereof to penetrate the sidewall portion 30. More specifically, theslits 32 are formed at six locations with an equal interval of 60degrees. Three of the slits 32 are disposed just below the electrodepins 70 to face the electrode pins 70, remaining three of the slits 32are disposed between the electrode pins 70 to not face the electrodepins 70.

As shown in FIG. 9, when the wafer 90′ is plated with the conventionalplating device 2′, the outer circumferential portion 92′ of the wafer90′ tends to have a larger plating thickness as opposed to that at thecenter portion 95′ of the wafer 90′. Further, the peripheral region 97′near the electrode pin 70′ tends to have a still larger platingthickness, thereby making it difficult to obtain a uniform platingthickness.

To this end, in the embodiment, it may be configured such that the slits32 disposed just below the electrode pins 70 have an opening areagreater than that of the slits 32 disposed between the electrode pins70. In this case, as opposed to a case that all of the slits 32 have anidentical opening area, it is possible to obtain a uniform platingthickness of the supply opening portion 120 over the entire surface ofthe wafer 90.

Second Embodiment

A second embodiment of the present invention will be explained next.FIG. 4 is a schematic sectional view showing the plating device 1 takenalong a line 4-4 in FIG. 2 according to the second embodiment of thepresent invention.

As shown in FIG. 4, different from the first embodiment, the platingdevice 1 includes a shutter portion 34 disposed on a front side of theslit 32 to be slidable in a horizontal direction. Other configurationsof the plating device 1 in the second embodiment are similar to those inthe first embodiment. The shutter portion 34 may be disposed on thefront side of each of the slits 32.

In the embodiment, when the shutter portion 34 slides in the horizontaldirection, it is possible to adjust an opening size of the slit 32.Accordingly, it is possible to adjust an amount of the plating solution60 flowing outside the cup portion 20 from the plating solution bath 21through the slit 32. When the shutter portion 34 is disposed on thefront side of the slit 32, it is possible to adjust the amount of theplating solution 60 flowing outside the cup portion 20 from the platingsolution bath 21 through the slit 32.

Third Embodiment

A third embodiment of the present invention will be explained next. FIG.5 is a schematic sectional view showing the plating device 1 taken alongthe line 4-4 in FIG. 2 according to the third embodiment of the presentinvention.

As described above, in the second embodiment shown in FIG. 4, theshutter portion 34 is disposed to be slidable in the horizontaldirection. In the third embodiment, the shutter portion 34 is disposedto be slidable in a vertical direction. The shutter portion 34 may bedisposed on the front side of each of the slits 32.

In the embodiment, when the shutter portion 34 slides in the verticaldirection, it is possible to adjust the opening size of the slit 32.Accordingly, it is possible to adjust the amount of the plating solution60 flowing outside the cup portion 20 from the plating solution bath 21through the slit 32. When the shutter portion 34 is disposed on thefront side of the slit 32, it is possible to adjust the amount of theplating solution 60 flowing outside the cup portion 20 from the platingsolution bath 21 through the slit 32.

Fourth Embodiment

A fourth embodiment of the present invention will be explained next.FIG. 6 is a schematic plan view showing the plating device 1 in a statethat the wafer pressing member 88 is omitted according to the fourthembodiment of the present invention.

As shown in FIG. 6, the slits 32 are disposed just below the electrodepins 70 with an equal interval of 120 degrees to face the electrode pins70. In other words, different from the first embodiment, the slits 32are not disposed between the electrode pins 70. Other configurations ofthe plating device 1 in the fourth embodiment are similar to those inthe first embodiment.

In the embodiment, the plating solution 60 flows out from the platingsolution bath 21 through the slits 32. Accordingly, a reduced amount ofthe plating solution 60 overflows through the space 82 between the upperedge portion 24 of the cup portion 20 and the wafer 90, so that areduced amount of the plating solution 60 contacts with the outercircumferential portion of the wafer 90. Accordingly, it is possible toprevent the thickness of the plating layer 120 from increasing at theouter circumferential portion of the wafer 90, thereby making itpossible to obtain the plating layer 120 with a uniform thickness overthe entire surface of the wafer 90.

In the first and second embodiments, the slits 32 are disposed not onlyjust below the electrode pins 70 but also between the electrode pins 70.Accordingly, it is possible to obtain the plating layer 120 with auniform thickness especially in a case in which a difference in thethickness of the plating layer 120 becomes large between the centerportion of the wafer 90 and the outer circumferential portion of thewafer 90. On the other hand, in the fourth embodiment, the slits 32 arenot disposed between the electrode pins 70. Accordingly, it is possibleto obtain the plating layer 120 with a uniform thickness especially in acase in which a difference in the thickness of the resist layer 112 isnot excessively large between the center portion of the wafer 90 and theouter circumferential portion of the wafer 90. In addition to obtainingthe plating layer 120 with a uniform thickness over the entire surfaceof the wafer 90, as compared with the first embodiment, it is possibleto form the plating layer 120 at a faster rate.

Fifth Embodiment

A fifth embodiment of the present invention will be explained next. Inthe fifth embodiment, the slits 32 are disposed just below the electrodepins 70 with an equal interval of 120 degrees to face the electrode pins70. In other words, different from the first embodiment, the slits 32are not disposed between the electrode pins 70. Further, in the fifthembodiment, the shutter portion 34 is disposed to be slidable in thehorizontal direction (refer to FIG. 4) or in the vertical direction(refer to FIG. 5). The shutter portion 34 may be disposed on the frontside of each of the slits 32. Other configurations of the plating device1 in the fifth embodiment are similar to those in the first embodiment.

As explained, in the fifth embodiment, the shutter portion 34 isdisposed on the front side of the slit 32. Accordingly, it is possibleto more precisely adjust the amount of the plating solution 60 flowingoutside the cup portion 20 from the plating solution bath 21 through theslit 32.

The disclosure of Japanese Patent Application No. 2010-142853, filed onJun. 23, 2010, is incorporated in the application by reference.

While the invention has been explained with reference to the specificembodiments of the invention, the explanation is illustrative and theinvention is limited only by the appended claims.

1. A plating device for plating a substrate, comprising: a platingsolution container for retaining a plating solution, said platingsolution container including a sidewall and an opening portionsurrounded with the sidewall; a holding member for holding the substrateso that the substrate faces the opening portion of the solutioncontainer and is situated away from the plating solution container; acathode electrode for contacting with an outer circumferential portionof the substrate; an anode electrode for contacting the plating solutionin the plating solution container; a plating solution supply device forsupplying the plating solution into the plating solution container sothat the plating solution overflows through a space between the platingsolution container and the substrate after the plating solution contactswith the substrate; and a through hole formed in the sidewall of theplating solution container.
 2. The plating device according to claim 1,wherein said through hole is arranged at a location to face the cathodeelectrode.
 3. The plating device according to claim 1, wherein saidthrough hole is arranged at a location to face the cathode electrode anda location away from the cathode electrode.
 4. The plating deviceaccording to claim 1, further comprising an opening size adjustingmember for adjusting an opening size of the through hole.